(a) Field of the Invention
The present invention relates to a differential amplifier, and more particularly, to an offset correction apparatus for a differential amplifier that compensates a direct current (DC) offset voltage in a differential analog signal amplifier using a resistive feedback structure to minimize a deviation and a method thereof.
(b) Description of the Related Art
FIG. 3 is an exemplary schematic diagram illustrating a general fully-differential amplifier. Referring to FIG. 3, the fully-differential amplifier 10 having a resistive feedback structure is configured to amplify a signal by an amplification factor set by receiving two signals A having a phase of 180 degrees as inputs. In particular, only when DC components of the two input signals match exactly, is a signal amplified by an amplification factor which is determined in the form of “B” output.
However, when the DC components of the two input signals do not exactly match, a difference between the DC components is increased by the amplification factor to cause a signal in the form of “C” to appear at an output terminal. Further, even though the DC components of the input signals match, DC offset may occur due to asymmetrical components of the amplifier 10. When a predetermined size or greater of DC offset occurs in a circuit having a substantially large amplification factor, differences in DC voltages of the output signals are significant and, the circuit may be saturated beyond the maximum or minimum voltage.
The above information disclosed in this section is merely for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.